Drop of egg production in chickens by experimental infection with an avian metapneumovirus strain PLE8T1 derived from swollen head syndrome and the application to evaluate vaccine

Decreases in egg production and increased incidence of abnormal eggs due to malformation of egg shells were observed in specific pathogen free (SPF) 173-day-old laying hens inoculated intravenously with an avian metapneumovirus (aMPV) strain PLE8T1. This strain was derived from an isolate from broiler birds exhibiting swollen head syndrome (SHS). Some SPF birds inoculated with the virus showed, slight diarrhea without any respiratory symptoms. Thus, the PLE8T1 strain was used as a challenge virus to evaluate efficacy of aMPV vaccines. SPF chickens which received a live attenuated aMPV vaccine (NEMOVAC; Merial) at 7 or 77 days old and an inactivated aMPV vaccine (OVO-4; Merial) at 105 days old were protected against poor egg production caused by the challenge with the PLE8T1 strain. Thus, aMPV, the PLE8T1 strain passaged 22 times after isolation, from birds exhibiting SHS, could induce a drop in egg production in laying hens accompanied by malformation of egg shells. It was suggested that this challenge system could be applied to evaluate the efficacy of aMPV vaccine.     

Effect of intermittent administration of sustained release isosorbide dinitrate (sr-ISDN) in rats with pressure-overload heart

Recent studies have demonstrated the benefits of nitric oxide (NO) on myocardial hypertrophy and myocardial fibrosis. It was suggested that NO has a protective effect on myocardial cell through the neurohormonal system. This effect serves to highlight the important role of NO in maintaining the function and form of heart with chronic heart failure. However, there are no known reports about on the effect of prolonged administration of nitrate on pressure over-load heart. This study was conducted to examine the long-term effect of oral nitrate therapy in rats with pressure-overloaded heart. An abdominal aorta constricted (AC) model of pressure-overloaded heart was created in male Wistar rats. Sustained release isosorbide dinitrate (sr-ISDN) (5 mg/kg once a daily) was administered to the rats once a daily for 12 weeks. The animals were euthanized during the study period, and the heart was collected and weighed. Histopathological examination was performed to evaluate the effect of sr-ISDN on myocardial hypertrophy and fibrosis. The ratio of heart to body weight increased significantly in AC rat and this increase was significantly prevented by sr-ISDN treatment. Histopathological examination showed significant increase in fibrotic area of AC rat compared to sham rat, this increase was inhibited by sr-ISDN treatment. Cardiomyocyte transverse diameter was significantly increased in AC rat compared with sham rat, but this increase tended to decrease by sr-ISDN treatment. In conclusion, intermittent administration with sr-ISDN has mild effect in inhibiting cardiac hypertrophy and marked effect in inhibiting fibrosis due to pressure-overload.     

Induction of neutralizing antibodies against bovine leukosis virus in rabbits by vaccination with recombinant vaccinia virus expressing bovine leukosis virus envelope glycoprotein

Three kinds of recombinant vaccinia virus (RVV)--mO-HA/ATI, LO1-HA/ATI and mO-HA/7.5kD--expressing bovine leukosis virus (BLV) envelope glycoprotein (gp60) were constructed. The BLV envelope gene of RVV mO-HA/ATI and LO1-HA/ATI or of RVV mO-HA/7.5kD was expressed under control of the promoter of A-type inclusion body (ATI) protein gene of cow-pox virus or vaccinia virus 7.5-kD protein gene, respectively. The vaccinia virus strain, LC16mO, was used as vector for RVV mO-HA/ATI and mO-HA/7.5kD, and strain LO-1 was used for RVV LO1-HA/ATI. Strains LC16mO and LO-1 are attenuated vaccine virus strains originating from the Lister original vaccinia virus. All 3 kinds of constructed RVV expressed gp60 in cultured rabbit kidney cells after infection; mO-HA/ATI expressed more antigen than did mO-HA/7.5kD. Rabbits vaccinated with RVV produced considerable antibody capable of inhibiting syncytium formation, as well as antibody with virion-binding ability. The RVV that used ATI promoter induced higher antibody titer than did the RVV that used 7.5-kD promoter. Results indicate that BLV gp60 is responsible for induction of neutralizing antibodies that suppress in vitro formation of syncytia among BLV-infected cells. Applicability of RVV, especially those using ATI promoter, was evaluated in a vaccine against bovine leukosis.     

Effect of Fucoidan Extracted from Mozuku on Experimental Cartilaginous Tissue Injury

We investigated the effect of fucoidan, a sulfated polysaccharide, on acceleration of healing of experimental cartilage injury in a rabbit model. An injured cartilage model was surgically created by introduction of three holes, one in the articular cartilage of the medial trochlea and two in the trochlear sulcus of the distal femur. Rabbits in three experimental groups (F groups) were orally administered fucoidan of seven different molecular weights (8, 50, 146, 239, 330, 400, or 1000 kD) for 3 weeks by screening. Control (C group) rabbits were provided water ad libitum. After the experimental period, macroscopic examination showed that the degree of filling in the fucoidan group was higher than that in the C group. Histologically, the holes were filled by collagen fiber and fibroblasts in the C group, and by chondroblasts and fibroblasts in the F groups. Image analysis of Alcian blue- and safranin O-stained F-group specimens showed increased production of glycosaminoglycans (GAGs) and proteoglycans (PGs), respectively. Some injured holes were well repaired both macroscopically and microscopically and were filled with cartilage tissues; cartilage matrices such as PGs and GAGs were produced in groups F 50, F 146, and F 239. Thus, fucoidan administration enhanced morphologically healing of cartilage injury.     

Effects of high potassium chloride supplementation on water intake, urine volume and nitrogen balance in mice

Sixteen ICR male mice were assigned to a control diet group or a KCl diet group in metabolic cages to clarify the effects of KCl supplementation on water intake, urine volume and N balance, and 5% of KCl was supplemented in KCl diets for 4 or 8 weeks. Bodyweight of KCl supplemented mice was significantly higher than that of control mice from 24 to 28 days after treatment. Feed intake, water intake and urine volume of KCl supplemented mice were significantly higher than those of control mice, and the increased water intake and urine volume in KCl supplemented mice were 4.49 and 4.15 g, respectively. Urinary N, K and Cl excretion were significantly higher in KCl supplemented mice. Although N retention was not significantly different between control and KCl supplemented mice, N retention in KCl supplemented mice tended to be lower. Serum creatinine concentration at 8 weeks after treatment was lower in KCl supplemented mice. Histological alteration using hematoxylin-eosin and Sirius red staining was not found in the kidney of each mouse at 4 and 8 weeks after treatment. These results suggest that high KCl supplementation increases water intake, urine volume and urinary N excretion in mice.     

水分胁迫条件下臭柏匍匐茎的蒸腾和吸水特性

在臭柏长期室内石砾土栽培条件下,通过培养液中加入PEG以调节溶液渗透势,设置对照区(pF值3.0)、水分胁迫区(pF值2.3)2种处理,并分别从匍匐茎中部人工培养不定根,测定有不定根和无不定根匍匐茎小枝的蒸腾速率、气孔导度及其水势的日变化和叶片水分特性.结果表明:1)在水分胁迫条件下,匍匐茎先端小枝通过降低正午水势提高吸水能力;基部小枝通过控制蒸腾,维持枝条水势防止失水.2)有不定根的匍匐茎通过降低质壁分离时的水势(ψwtlp)和充分吸水时的渗透势(ψ,ssat)提高吸水能力,而且增加细胞弹性率,迅速降低膨压保证失水时能尽快关闭气孔;而无不定根匍匐茎虽然吸水能力较差,但细胞壁柔软,即使蒸腾失水,也能在较长时间内维持膨压,保证生命活动进行.     

High nitrate reductase activity in sprouts of Phyllostachys pubescens

We investigated the distribution of nitrate reductase activity (NRA) among leaves, roots, culms, twigs, sprouts, culm sheaths, and new leaves of Phyllostachys pubescens Mazel in May, when many sprouts emerge above ground and new leaves of adult culms expand. We found that the NRA differed among parts, and that sprouts showed high NRA. These results indicate that different tissues of P. pubescens vary in nitrate reduction, and sprouts possess high nitrate reduction capacity. We also found that culm sheaths showed high NRA, indicating that they have a high potential for nitrate reduction, even though they are shed in the way of sprout growth.     

Characterization of the neurotoxin produced by isolates associated with avian botulism

Several varieties of birds are affected by type C botulism. We conducted neutralization tests of culture supernatants of isolates from cases of avian botulism. Whereas the toxin produced by isolates derived from mammalian botulism was neutralized only with type C antitoxin, the toxins of all isolates related to avian botulism were neutralized with both type C and D antitoxins. An analysis of nucleotide sequences with several strains revealed that the neurotoxin gene in the isolates from avian botulism comprises two thirds of the type C neurotoxin gene and one third of the type D neurotoxin gene. This indicates that the neurotoxin of avian isolates is a mosaic of type C and D neurotoxins. We prepared three sets of primers to differentiate the gene for the mosaic form from the conserved genes of type C and D neurotoxins. The results of polymerase chain reaction with these primers indicated that all avian botulism-related isolates and specimens possess the gene for the mosaic form of the neurotoxin. The toxins purified from avian and mammalian isolates exhibited the same degree of lethality in mice, but the former showed greater toxicity to chickens than the latter. These results indicate that the mosaic neurotoxin is probably a pathogenic agent causing some forms of avian botulism.